Default [Q] CM10 Galaxy S3 won't mount external SD

Phone: Unlocked (AT&T) rooted Galaxy S3 running Cyanogenmod 10

My phone will not recognize my 64gb external SD card. If I take it out and put it back in, it'll say "preparing SD" for about 5 seconds and then do nothing. If I try and mount it through the settings the mount sd option is greyed out. I've tried every combination of restarting and putting it back in possible.
I'm scared I might have fried it for good while messing around trying to get it to mount as a USB. Through some miraculous kludgy combination of apps and scripts, I managed to do it, but after I disconnected it from my computer the phone would not recognize it, and now my computer (a mac if that matters) won't either. The phone recognized it fine before all this.

Again, not sure exactly how I got it to mount as USB but it was some combination of these:

At this point I don't even care if it'll mount as USB, I just want my SD card back. Total noob here, please have mercy.